tag:blogger.com,1999:blog-5573426.post4009580292476713617..comments2024-02-20T15:17:48.594+11:00Comments on A.E.Brain: The Complexities of LifeZoe Brainhttp://www.blogger.com/profile/13712045376060102538noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-5573426.post-31408368745039140632010-11-05T03:27:12.960+11:002010-11-05T03:27:12.960+11:00@mythusmage-
I'll admit my ignorance as to m...@mythusmage- <br /><br />I'll admit my ignorance as to myxobacteria. However, from the reference you cited, it looks like they are bacteria that swarm, work together, and specialize. In other words, they have some of the features of multi-cellular life forms, but not all - for example, there aren't specialized tissues. The analogy you make with slime molds is a good one.<br /><br />In any case, your taxonomy is incorrect; neither is in the kingdom Animalia. Slime Molds are usually classified as Excavata (or Acrasidae - depends on who you ask), Chromalveolata, or Rhizaria (depending on the kind), whereas myxobacteria are Bacteria.<br /><br />@anonymous - Carl Sagan? The same astronomer who loves the Drake equation (which itself is a model with multiple poor inputs)? I think he likes models, he might just disagree on the model or its inputs.Zimbelnoreply@blogger.comtag:blogger.com,1999:blog-5573426.post-41087577055909110912010-11-04T12:04:23.542+11:002010-11-04T12:04:23.542+11:00Carl Sagan would disagree. When numbers are so lar...Carl Sagan would disagree. When numbers are so large and time an unsure factor anything can happen, it is called the unknown. We do not have all the factors to make good datum. So play modleing all you want something is still missing.<br /><br />MACAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-5573426.post-69698995137764133222010-11-04T09:57:30.915+11:002010-11-04T09:57:30.915+11:00I get the feeling certain parties don't unders...I get the feeling certain parties don't understand what myxobacteria are. In a word, myxobacteria are multicellular life forms, slime molds in short, based on bacteria instead of eukaryotic cells. Bacterial slime molds, with all the features of standard slime molds. Including cell differentiation, fruiting bodies, and specialized cells for procreation. When you consider how little it took to get one eukaryotic slime mold recognized as a primitive animal, the leap to a bacterial animal isn't that hard for myxobacteria to make.mythusmagehttps://www.blogger.com/profile/10458869083534878283noreply@blogger.comtag:blogger.com,1999:blog-5573426.post-86292096087060857622010-11-04T02:31:10.858+11:002010-11-04T02:31:10.858+11:00Some of the most disparate Genetic codes are from ...Some of the most disparate Genetic codes are from Mitochondria. I think perhaps a good way to try to date Eukaryotes would be to try to map out mitochondrial DNA variance, much as doing so in Humans alone gives us a guess on Mitochondrial Eve.<br /><br />I have no idea if such an approach is feasible, though; my Biology is archaic, particularly in the area of genetics. There are a lot more mitochondrial generations than human ones, particularly along certain lines.Zimbelnoreply@blogger.comtag:blogger.com,1999:blog-5573426.post-36240449084290651622010-11-03T20:57:18.934+11:002010-11-03T20:57:18.934+11:00One think that could give us an indication of the ...One think that could give us an indication of the likelihood of the development of complex cells is how soon did they develop after sufficient oxgen became available. The more likely their development was, the sooner they would probably have developed.<br /><br />The oldest eukaryotes that we are certain of are from 1.2 billion years ago. There are possible eukarote fossils from as much as 2.1 billion years ago. There are possible biomarkers from 2.7 billion years ago.<br /><br />If the last figure is correct then they probably evolved nearly as soon as they could have. If they evolved considerably later then they could well have originated in a fluke event.Lloyd Flackhttps://www.blogger.com/profile/00832519369660328832noreply@blogger.comtag:blogger.com,1999:blog-5573426.post-53139276038621377772010-11-03T19:08:25.539+11:002010-11-03T19:08:25.539+11:00You have read up on the myxobacteriaYou have read up on the <a href="http://www.google.com/search?q=myxobacteria&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a" rel="nofollow">myxobacteria</a>mythusmagehttps://www.blogger.com/profile/10458869083534878283noreply@blogger.comtag:blogger.com,1999:blog-5573426.post-4396340153566346522010-11-03T03:45:55.259+11:002010-11-03T03:45:55.259+11:00While I agree that eukaryote almost certainty evol...While I agree that eukaryote almost certainty evolved only once, I'd make a stronger statement - it seems that prokaryotes may also have evolved only once; more to the point, we have little evidence that they didn't.<br /><br />Where is my claimed evidence or lack thereof? In the genetic codes themselves. Even in genetic codes that are widely disparate (say the Yeast Mitochondrial code versus the human nuclear code), there are striking simularities. <br />In that particular case, 8 of the 64 codons code for something different than each other; random chance would suggest far higher numbers.<br /><br />So one of three things is making these genetic codes similar:<br />1) Our sample is biased towards similar genetic codes - i.e. we haven't found vastly different ones yet.<br />2) These codes are heavily related to each other, likely coming from a common ancestor.<br />3) The chemistry itself is highly biased towards specific genetic codes. Note that there is <a href="http://www.springerlink.com/content/b418465308240147/fulltext.pdf" rel="nofollow">evidence</a> of this.<br /><br />I tend to favor #2 and #3, although obviously a future discovery of a very different genetic would disproove #2.<br /><br />A site on genetic codes, updated a few months ago: <a href="http://www.ncbi.nlm.nih.gov/Taxonomy/Utils/wprintgc.cgi?mode=c#SG3" rel="nofollow">The Genetic Codes Compiled by Andrzej (Anjay) Elzanowski and Jim Ostell National Center for Biotechnology Information (NCBI), Bethesda, Maryland, U.S.A.</a>Zimbelnoreply@blogger.comtag:blogger.com,1999:blog-5573426.post-3291373186273348882010-11-02T22:38:36.068+11:002010-11-02T22:38:36.068+11:00There is no genetic evidence of eukaryotes evolvin...There is no genetic evidence of eukaryotes evolving more than once. They could not evolve until there was enough oxygen available for aerobic metabolism. When they did evolve I would expect them to have diversified until they took up all the available niches for such organisms, pre-empting any second evolution of complex cells.Lloyd Flackhttps://www.blogger.com/profile/00832519369660328832noreply@blogger.com